My ideal business app layout (I assume we are talking enterprise, here) would be: DB: A hybrid of Postgres & MongoDB API: Hand rolled w/ SparkJava Front End:

My ideal business app layout (I assume we are talking enterprise, here) would be: DB: A hybrid of Postgres & MongoDB API: Hand rolled w/ SparkJava Front End: intercooler.js (SPAs blow out your complexity budget, which should be spent on business logic) Caching: Redis PaaS: the system should be designed to deploy on anything, including internal servers For a SaaS app, I would look at rails due to the ecosystem and stability, but otherwise it would remain the same.